You may like having Vista's pretty-fying Aero effects enabled while you're working, but many modern games can make you want to devote every last bit of memory and power to their 3-D awesomeness. The How-To Geek shows how to easily disable desktop effects by editing (or creating) a shortcut for the game (or other program):

Simply right-click on the shortcut and choose Properties, and then the Compatibility tab ... Now on the Settings block check the box for "Disable desktop composition" in order to disable Aero the next time you use the shortcut.

I have to guess many people might have never found that tweak, based on its obscure label, but it sure comes in handy.